Transcript Figure 1.1 The various parts of the scientific method.

Matter
Overview
Learn about the composition of matter
 Learn the difference between elements
and compounds
 Distinguish between physical and
chemical properties and changes
 Distinguish between mixtures and pure
substances
 Learn 2 methods of separating mixtures
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Did you ever wonder?...
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How do plants grow & why are they green?
Why is the sun hot?
Why does a hot dog get hot in a microwave?
Why does wood burn and rocks do not?
How does soap work?
Why does pop fizz?
What’s happening when iron rusts?
Why doesn’t aluminum foil rust?
How does a hair permanent work?
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The Particulate Nature of Matter
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Matter: the “stuff” the universe is
composed of
 Has mass and occupies space
 Comes in many forms: the stars, your chair,
brain tissue
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Composed of tiny particles called atoms
 Scanning tunneling microscope produces
images of atoms
 Can’t see with naked eye, similar to looking at
beach from far away; can only see sand
particles when you get close
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Elements and Compounds
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Atoms: all matter is composed of these tiny
particles
 Over 100 different atoms
 Similar to words, all made from 26 different letters
 All matter made from about 100 different atoms
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Compounds: substances made by bonding
atoms together in specific ways
 Contain 2 or more different types of atoms
 Same throughout
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Molecule: made up of atoms that are “stuck”
together
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Atom Combinations
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Elements
Some atoms can combine with
like atoms to form molecules: H2
& O2
 Carbon bonds forming large
groups
 Elements: substances that
contain only one type of atom
 Compound: always contains
atoms of different elements
(water = H2O)
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Top
Ten
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Figure 2.5:
The three
forms of the
element
carbon:
Diamond.
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Figure 2.5: The
three forms of
the element
carbon:
Graphite.
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Figure 2.5: The
three forms of the
element carbon:
Buckminsterfullerene.
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The States of Matter
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Figure 2.7: The three
states of water: Solid.
Solids: Rigid; have a
fixed shape and volume
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Figure 2.7: The three
states of water: Liquid
Liquid: has a definite
volume but takes the
shape of its container
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Figure 2.7: The three
states of water: Gas.
Gas: has no fixed
volume or shape;
uniformly fills any
container
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Physical and Chemical Properties and Changes
Physical Properties: Odor, color, volume,
state, density, melting point, and boiling
point
 Chemical properties: refer to a substances
ability to form new substances
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 Examples: wood burning, rusting of steel,
digestion of food, growth of grass
 Given substance changes to a fundamentally
different substance or substances
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Chemical vs. Physical change in water
 Physical changes
solid → liquid → gas
 Change of state: H2O molecules still present
 Chemical change = electrolysis
 water changed into different substances (water
decomposes to hydrogen & oxygen)
Electrolysis, the
decomposition of
water by an
electric current, is
a chemical
process.
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Physical & Chemical Changes
 Physical
change involves a change in one
or more physical properties, but no change
in fundamental components of substance.
Most common are changes in state.
 Chemical
change involves a change in the
fundamental components of the substance.
Chemical changes are called reactions.
Mixtures and Pure Substances
 Mixture: something that has variable composition
 Examples: soda, coffee, tap water, air
 Composition of mixtures varies, but composition of
compounds is always the same
 Composition depends on how much of each component
is used when mixture is formed
 Can be separated into pure substances: elements
and/or compounds
The composition of air.
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Chart examining each substance
of air.
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Mixtures: Alloys
 Alloys:
mixtures of metals
 Many gold alloys: mixture of gold, copper, and
silver
 They are not compounds! (like water)
 Composition varies
Figure 2.10: Twenty-four-karat gold is an
element
Eighteen-karat gold is an alloy.
Fourteen-karat gold is an alloy.
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Homogeneous and Heterogeneous
 Homogeneous mixture is the same throughout, &
also called a solution
 Examples: salt water, air, brass (mixture of
copper and zinc)
 Heterogeneous mixture contains regions that have
different properties from other regions
 Examples: sand/water mixture, rocky road ice
cream, chocolate chip cookie dough
Representation of H2O molecules.
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Distillation: Separation Process
 Boil
water (or other liquid)
 Vaporizes (turns into gas = steam)
 Condense (cool steam in tube) – turns
back to liquid
 Minerals are left behind
 Pure water collected
 Physical change
The solution is boiled and steam is driven off.
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Salt remains after all water is boiled off.
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No chemical change occurs when salt water is
distilled.
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Filtration: Separation Process
 Pour
mixture onto a mesh, such as filter
paper
 Liquid passes through, solid is left behind
on filter paper
Filtration
separates a
liquid from a
solid.
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Separation of a sand-saltwater mixture.
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Pure Substances
 Pure
substances are either elements or
compounds
 Always have same chemical and physical
properties
The organization of matter.
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Setup to boil water.
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